Valve arrangements have long been known which are suitable for monitoring the control of fluid flow through tubs in various types of procedures and in various types of apparatus as described in my co-pending application Ser. No. 484,205, filed Apr. 12, 1983.
Procedures have long been known involving the introduction of fluids into the vascular systems of patients. These have developed to a point of employing a source of fluid for intravenous procedures and connecting such source via a pump through a needle or catheter into the vascular system. The pump itself has been developed to a point that when connecting catheters are accidentally opened to ambient atmosphere, the pumping operation is terminated thereby to reduce the possibilities of air being introduced into the vascular system. This is necessary because the introduction of air will cause an embolism which in turn may be fatal to the patient being treated. Nevertheless, the use of such a pump, which is commercially available, is not always effective to prevent accidents of the aforenoted typed in all cases. Thus, for example, when the intravenous tubing is coupled to a catheter on the down stream side of the pump, and this catheter becomes accidentally opened to ambient atmosphere, the pressure differential between ambient atmosphere and the vascular system in which the distal tip of the catheter resides is such as to cause air to be sucked through the catheter into the vascular system. This accidental occurrence has been known to cause serious harm to the patient being treated. A number of patents have been found to deal with intravenous procedures and problems of the aforenoted type, as well as to related systems exposed to pressure differential or the like. These patents include U.S. Pat. Nos. 2,538,662; 3,570,808; 3,599,670; 3,888,249; 4,103,686; 4,252,166; 4,324,239; and 4,335,747.
C. Abbott in U.S. Pat. No. 2,538,662 discloses a surgical apparatus for the intravenous administration of liquids, such as whole blood, blood plasma, destrose solutions, and the like and is directed particularly to an expendable valve unit construction used in such surgical apparatus.
J. Wren, in U.S. Pat. No. 3,570,808 discloses a coupling assembly for releasably attaching an air hose to a regulator of the type used in conjunction with the face mask of an underwater diving apparatus. The coupling is readily detachable and a valve mechanism is provided so that when the air hose is decoupled from the regulator underwater, the valves provided in the regulator air inlet and in the end of the air hose are immediately biased to a closed position. Such a construction and arrangement might have utilization in connection with intravenous procedures.
In U.S. Pat. No. 3,599,670, J. Gurner discloses a fluid coupling with a valve means having such provision that if a maximum rate of flow through a hose is exceeded as, for example, by leakage, the coupling valve will close and prevent further flow.
In U.S. Pat. No. 3,888,249, D. Spencer discloses a catheter for prolonged infusion of medication into an artery. The catheter is provided with a tip designed employing a flap valve principle to assure uniform and steady diffusion of the medication into the blood stream and to inhibit retrograde flow of blood into the catheter thereby to minimize clotting and blockage of medication flow.
In U.S. Pat. No. 4,103,686, R. LeFevre discloses a dual valve assembly for intravenous infusions from multiple parenteral fluid sources. The assembly controls forward and reverse flow through a flow line and includes normally seated first and second valves mounted for movement toward and away from respective valve seats to control flow in such a manner as to prevent reverse flow through the assembly.
M. Gordon shows in U.S. Pat. No. 4,324,239, a safety valve for preventing air embolism and hemorrhage. The safety valve disclosed is useful for catheterization procedures and is characterized by a piston having an internal flow path and so arranged as to be biased to a closed position. The arrangement is such as to prevent air embolism and hemmorhage.
In U.S. Pat. No. 4,355,747, is disclosed an arrangement which is effective to exclude air or other undesirable gas in a connecting procedure.
None of the aforegoing patents, nor any of the other arrangements known heretofore, is effective to the same degree as the structure to be described below in the preventing of the introduction of air into the vascular system of a patient.